Adsorption of Cr(VI), Pb(II) Ions and Methylene Blue Dye from
Aqueous Solution using Pristine and Modified Coral Limestone

This work reports the feasibility of using pristine and chemically modified coral limestones by acid and base. Their potential adsorptive capabilities is probed by treatment of toxic Cr(VI), Pb(II) ions and methylene blue in aqueous solution under different experimental parameters by batch method. Parameters such as agitation time, concentration, temperature and pH were varied to understand the sorption behaviour of the adsorbents in each case. The adsorbents were characterized by SEM, XRD and FTIR. Morphological analysis by SEM micrographs show that the surface of all adsorbents was irregular in nature. XRD spectra confirmed the orthorhombic structure of aragonite in the pristine coral limestones (PCL), acid modified coral limestones (ACL) and base modified coral limestones (BCL). FTIR results affirmed the presence of (CO3 2-) and (-C=O) groups of the carbonate ions and Ca-O attachment to the surface of PCL and removal of CaCO3 characteristic peaks in ACL and BCL. However, in the modified adsorbents shifting of Ca-O peaks occurred. The recorded maximum adsorption capacities of PCL, ACL and BCL for Cr(VI) ions were 69.42, 65.04, 64.88 mg/g, Pb(II) ions 39.36, 74.11, 78.34 mg/g and methylene blue 37.24, 46.28, 46.39 mg/g, respectively. The uptake of Pb(II), Cr(VI) ions, methylene blue onto PCL fitted Freundlich model. Also the uptake of Cr(VI) ions and methylene blue onto ACL and BCL fitted Freundlich isotherm. However, uptake of Pb(II) ions onto both ACL and BCL fitted Langmuir isotherm. The data revealed that the adsorption of Pb(II) ions onto PCL and ACL and methylene blue dye onto PCL was exothermic. Whilst the adsorption of Cr(VI) ions onto PCL, ACL and BCL and methylene blue dye onto ACL and BCL were endothermic in nature, hence increasing the temperature would enhance the uptake of Pb(II) ions onto BCL, Cr(VI) ions onto ACL and BCL and methylene blue onto ACL and BCL. The obtained (ΔGº) values at all studied temperatures for the adsorption of Pb(II), Cr(VI) ions and methylene blue onto PLC, ACL and BCL indicated a spontaneous process.

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Using of modified-bentonite as low-cost sorbent for removal of methylene blue dye from aqueous solution

Association of Arab Universities Journal of Engineering Sciences ◽

10.33261/jaaru.2020.27.2.005 ◽

2020 ◽

Vol 27 (2) ◽

pp. 45-54

Author(s):

Saraa Muwafaq Ibrahim ◽

Ziad T. Abd Ali

Keyword(s):

Aqueous Solution ◽

Methylene Blue ◽

Silanol Group ◽

Infrared Spectrometry ◽

Blue Dye ◽

Ammonium Bromide ◽

Vibration Band ◽

Order Kinetic ◽

Methylene Blue Dye ◽

Modified Bentonite

Batch experiments have been studied to remove methylene blue dye (MB) from aqueous solution using modified bentonite. The modified bentonite was synthesized by replacing exchangeable calcium cations in natural bentonite with cationic surfactant cetyl trimethyl ammonium bromide (CTAB). The characteristics of modified bentonite were studied using different analysis such as Scanning electronic microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and surface area. Where SEM shows the natural bentonite has a porous structure, a rough and uneven appearance with scattered and different block structure sizes, while the modified bentonite surface morphology was smooth and supplemented by a limited number of holes. On other hand, (FTIR) analysis that proved NH group aliphatic and aromatic group of MB and silanol group are responsible for the sorption of contaminate. The organic matter peaks at 2848 and 2930 cm-1 in the spectra of modified bentonite which are sharper than those of the natural bentonite were assigned to the CH2 scissor vibration band and the symmetrical CH3 stretching absorption band, respectively, also the 2930 cm-1 peak is assigned to CH stretching band. The batch study was provided the maximum removal efficiency (99.99 % MB) with a sorption capacity of 129.87 mg/g at specified conditions (100 mg/L, 25℃, pH 11 and 250rpm). The sorption isotherm data fitted well with the Freundlich isotherm model. The kinetic studies were revealed that the sorption follows a pseudo-second-order kinetic model which indicates chemisorption between sorbent and sorbate molecules.

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Citric acid modified waste cigarette filters for adsorptive removal of methylene blue dye from aqueous solution

Journal of Applied Polymer Science ◽

10.1002/app.50655 ◽

2021 ◽

pp. 50655

Author(s):

Aafia Tehrim ◽

Min Dai ◽

Xiange Wu ◽

Malik Muhammad Umair ◽

Imran Ali ◽

...

Keyword(s):

Aqueous Solution ◽

Methylene Blue ◽

Citric Acid ◽

Blue Dye ◽

Methylene Blue Dye ◽

Adsorptive Removal

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The Removal of Methylene Blue Dye from Aqueous Solutions Using Activated and Non-Activated Bentonites

Adsorption Science & Technology ◽

10.1260/026361703769645780 ◽

2003 ◽

Vol 21 (5) ◽

pp. 451-462 ◽

Cited By ~ 22

Author(s):

Sameer Al-Asheh ◽

Fawzi Banat ◽

Leena Abu-Aitah

Keyword(s):

Methylene Blue ◽

Ph Value ◽

Sodium Dodecyl ◽

Freundlich Isotherm ◽

Blue Dye ◽

Batch Adsorption ◽

Ionic Surfactant ◽

Methylene Blue Dye ◽

X Ray Diffraction ◽

Initial Ph

An improvement in the adsorption capacity of naturally available bentonite towards water pollutants such as Methylene Blue dye (MBD) is certainly needed. For this purpose, sodium bentonite was activated by two methods: (1) treatment with sodium dodecyl sulphate (SDS) as an ionic surfactant and (2) thermal treatment in an oven operated at 850°C. Batch adsorption tests were carried out on removing MBD from aqueous solution using the above-mentioned bentonites. It was found that the effectiveness of bentonites towards MBD removal was in the following order: thermal-bentonite > SDS-bentonite > natural bentonite. X-Ray diffraction analysis showed that an increase in the microscopic bentonite platelets on treatment with SDS was the reason behind the higher uptake of MBD. An increase in sorbent concentration or initial pH value of the solutions resulted in a greater removal of MBD from the solution. An increase in temperature led to an increase in MBD uptake by the bentonites studied in this work. The Freundlich isotherm model was employed and found to represent the experimental data well.

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